S

• SATA:
  Serial Advanced Technology Attachment. A computer bus designed to transfer data to and from a hard drive using serial signaling technology. Because SATA cables are thinner than its ribbon type counterpart, they can be connected to more devices while maintaining its signal integrity.
   
• Scalable:
  Basically, a scalable system or system architecture is one that can be modified in its size or configuration to suit changing conditions. As an example, a company that is set up to run a client/server type network may only have 10 people currently set up on the network, but the company plans to have many more set up in the coming years. In this instance, they would need to be able to make this network scalable.
   
• Scalar Processing:
  A process that calculates numbers in sequence.
   
• Scope:
  In computer programming, this would refer to a specific identifying enclosing context. Each programming language uses various types of scopes to accomplish different things.
   
• Screen Flicker:
  This is generally referring to the flickering of a display screen and can be caused by a number of factors, the most important of which is the monitor's refresh rate, or the speed that the screen is re-drawn. If the refresh rate is too slow, the screen will appear to glimmer. Another factor that affects screen flicker is the persistence of the screen phosphors. Low-persistence phosphors fade more quickly than high-persistence monitors, making screen flicker more likely. Screen flicker can also be affected by lighting. Finally, screen flicker is a subjective perception that affects people differently. Some people perceive screen flicker where others do not. Most people perceive no screen flicker if the refresh rate is 72 MHz or higher.
   
• SCSI:
  Abbreviation of "Small Computer System Interface". It is pronounced "scuzzy," and is a parallel interface standard used by Apple Macintosh computers, PCs, and many UNIX systems for the purpose of attaching peripheral devices to computer systems. Nearly all Apple Macintosh computers, excluding only the earliest Macs and the recent iMac, come with a SCSI port for attaching devices such as disk drives and printers.
  
  SCSI interfaces provide for faster data transmission rates (up to 80 megabytes per second) than standard serial and parallel ports. In addition, you can attach many devices to a single SCSI port, so that SCSI is really an I/O bus rather than simply an interface.
  
  The following varieties of SCSI are currently implemented:
  
  SCSI-1: Uses an 8-bit bus, and supports data rates of 4 MBps
  
  SCSI-2: Same as SCSI-1, but uses a 50-pin connector instead of a 25-pin connector, and supports multiple devices. This is what most people mean when they refer to plain SCSI.
  
  Wide SCSI: Uses a wider cable (168 cable lines to 68 pins) to support 16-bit transfers.
  
  Fast SCSI: Uses an 8-bit bus, but doubles the clock rate to support data rates of 10 MBps.
  
  Fast Wide SCSI: Uses a 16-bit bus and supports data rates of 20 MBps.
  
  Ultra SCSI: Uses an 8-bit bus, and supports data rates of 20 MBps.
  
  SCSI-3: Uses a 16-bit bus and supports data rates of 40 MBps. Also called Ultra Wide SCSI.
  
  Ultra2 SCSI: Uses an 8-bit bus and supports data rates of 40 MBps.
  
  Wide Ultra2 SCSI: Uses a 16-bit bus and supports data rates of 80 MBps.
   
• SDH:
  Synchronous Digital Hierarchy. A method used for multiplexing many circuits with a low bit rate onto fewer circuits with a higher bit rate, and vice-versa (de-multiplexing). Used primarily in the telecomms industry to carry telephony traffic. This network can also be used to carry IP traffic.
   
• SDRAM:
  Short for "Synchronous Dynamic Random Access Memory". This is a newer type of DRAM that has the ability to run at much higher clock speeds than conventional memory. SDRAM actually synchronizes itself with the CPU's bus and is capable of running at 100 MHz, about three times faster than conventional FPM RAM, and about twice as fast EDO DRAM and BEDO DRAM. SDRAM is replacing EDO DRAM in many newer computers.
  
  Today's fastest Pentium systems use CPU buses running at 100 MHz, so SDRAM can keep up with them, though barely. Future PCs, however, are expected to have CPU buses running at 200 MHz or faster. SDRAM is not expected to support these high speeds which is why new memory technologies, such as RDRAM and SLDRAM, are being developed.
   
• Secondary Cache:
  Also referred to as "Level 2 cache" or "L2". In general, L2 cache memory resides on a separate external chip from the microprocessor chip. However, The Pentium Pro processor has an L2 cache on the same chip as the microprocessor.
   
• Semantics:
  A relationship between words, phrases or any other allowable constraint and their actual meaning. This is contrast to "Syntax". An example could be; if you enter a misspelled command, it would be a syntax error, but if you enter what may be a legitimate command but is not understood in its current context, this would be a "semantics error".
   
• Semiconductor:
  This refers to a material that is not a good conductor of electricity (copper) nor a good insulator (plastic). Silicon and germanium are the most common semiconductor materials.
  
  Semiconductor materials are used in computer chips, both for CPU and memory. Its purpose is to create miniature electronic components that take up less space and require less energy.
   
• SEO:
  (Search Engine Optimization) SEO is a process of arranging a web site's content to obtain high rankings in various search engines (both the site and individual pages), and includes tailoring on-page text (such as headlines and subtitles) as well as choosing the proper keywords for a page's meta tags. 
   
• Serialization:
  A sequence of commands that execute orders in a database.
   
• Serial Port:
  A port, or interface, that can be used for serial communication, in which only 1 bit is transmitted at a time. Most serial ports on personal computers conform to the RS-232C or RS-422 standards. A serial port is a general-purpose interface that can be used for almost any type of device, including modems, mice, and printers (although most printers are connected to a parallel port).
   
• Server:
  This is a mainframe computer that serves the other computers attached to it.
   
• SGRAM:
  Abbreviation of "Synchronous Graphic Random Access Memory". This is a type of DRAM used commonly on graphics accelerators and video adapters. Like SDRAM, SGRAM can synchronize itself with the CPU bus clock up to speeds of 100 MHz.
   
• Shadowing:
  A technique used to increase a computer's speed by using high-speed RAM memory in place of slower ROM memory (RAM is about three times as fast as ROM). On PCs, for example, all code to control hardware devices, such as keyboards, is normally executed in a special ROM chip called the BIOS ROM. However, this chip is slower than the general-purpose RAM that comprises main memory. Many PC manufacturers, therefore, configure their PCs to copy the BIOS code into RAM when the computer boots. The RAM used to hold the BIOS code is called shadow RAM. 
   
• Shareware:
  Software distributed on the basis of an honor system. Most shareware is delivered free of charge, but the author usually requests that you pay a small fee if you like the program and use it regularly. By sending the small fee, you become registered with the producer so that you can receive service assistance and updates. You can copy shareware and pass it along to friends and colleagues, but they too are expected to pay a fee if they use the product.
  
  Shareware is inexpensive because it is usually produced by a single programmer and is offered directly to customers. Thus, there are practically no packaging or advertising expenses.
   
• Sheet Tab:
  In spreadsheet applications, this would refer to a tab at the bottom of a work sheet that acts as a means to identify or access different sheets within a workbook.
   
• Shell:
  Just like the shell of an egg is the outermost layer, in computer technology, this refers to the outermost layer of a program. Operating systems and applications sometimes provide an alternative shell to make interaction with the program easier. For example, if the application is usually command driven, the shell might be a menu-driven system that translates the user's selections into the appropriate commands. 
  
  Sometimes called command shell, a shell is the command processor interface. The command processor is the program that executes operating system commands. The shell, therefore, is the part of the command processor that accepts commands. After verifying that the commands are valid, the shell sends them to another part of the command processor to be executed.
   
• SID (Service ID):
  Used in the DOCSIS standard to defines a particular mapping between a cable modem (CM) and the CMTS. The SID is used for the purpose of upstream bandwidth allocation and class-of-service management.
   
• SIMM:
  Acronym for single in-line memory module, a small circuit board that can hold a group of memory chips. Typically, SIMMs hold up 8 (on Macintoshes) or 9 (on PCs) RAM chips. On PCs, the ninth chip is often used for parity error checking. Unlike memory chips, SIMMs are measured in bytes rather than bits. SIMMs are easier to install than individual memory chips.
  
  The bus from a SIMM to the actual memory chips is 32 bits wide. A newer technology, called dual in-line memory module (DIMM), provides a 64-bit bus. For modern Pentium microprocessors that have a 64-bit bus, you must use either DIMMs or pairs of SIMMs.
   
• Simplex:
  A one directional communications circuit that can only either transmit or receive, but not both. Two good examples of simplex devices would be your TV or an FM radio.
   
• SIP:
  Abbreviation of single in-line package, a type of housing for electronic components in which the connecting pins protrude from one side. Compare with DIP and PGA. A SIP is also called a Single In-line Pin Package (SIPP).
   
• Skype:
  This is a peer-to-peer voice over Internet protocol (VoIP). This Internet telephony network was created by the same people that created Kazaa (Niklas Zennström and Janus Friis). It was developed as a free desktop software application that gives users the ability to make free Internet phone calls to other Skype users or you can use the application to place and receive phone calls to and from traditional phone lines for a reduced fee.
   
• SLIP:
  Stands for Serial Line Interface Protocol. This is another application that allows for a connection to another computer.
   
• SMS (Short Message Service):
  A popular wireless service that is used for sending and receiving short messages up to a maximum of 160 characters. The service is used for text messaging between cell phones that are on a GSM (Global System for Mobile) network.
   
• SMTP:
  Stands for Simple Mail Transfer Protocol.
   
• SNMP:
  Stands for "Simple Network Management Protocol". It was developed in 1988 and has become a standard for Internet work management and used almost exclusively in TCP/IP networks.
   
• Socket:
  In computer technology, a Socket refers to a receptacle that provides a means of communication between two processes.
   
• Socket 7:
  Socket 7 is a connection format used on older processors such as the Cyrix M2, AMD K6 and K6-2.
   
• Socket 8:
  The Socket 8 connection format was exclusively used on Intel Pentium Pro and Pentium II OverDrive processors.
   
• SODIMM (Small Outline Dual Inline Memory Module):
  These memory modules are typically used in laptop and notebook computers where space and low power consumption is a major consideration. SODIMM's are about half the size of its DIMM counterpart.
   
• Software Modem:
  A modem implemented entirely in software. Software modems rely on the computer's processor to modulate and demodulate signals.
   
• Source Code:
  Computer programs or operating systems are originally written by a human being in a programming language. This is called the source code of the software. To be actually used by a computer, the program has to be translated by the computer from the source code into the machine language that the computer understands and can execute. This translation process is referred to as compiling.
   
• Software:
  This is a program, the actual code the computer reads. All other stuff is hardware. A floppy disc is hardware.
   
• Spam:
  This is to transmit unwanted messages, usually over email, to a great many people.
   
• Spoofing:
  To fool. In networking, the term is used to describe a variety of ways in which hardware and software can be fooled. Email spoofing, for example, involves trickery that makes a message appear as if it came from a legitimate business email address.
   
• Spooling:
  The process of storing a device (eg: printer) output signal in a queue, while the device can take on other actions. When the device is ready to take on other actions, it will draw from the queue.
  The term spooling is derived from the acronym "Spool": Simultaneous Peripheral Operations On-Line
   
• SQL:
  (Structured Query Language) A specialized programming language for sending queries to databases. Most industrial-strength and many smaller database applications can be addressed using SQL. Each specific application will have its own version of SQL implementing features unique to that application, but all SQL-capable database support a common subset of SQL. 
   
• SRAM:
  Short for static random access memory, and pronounced ess-ram. SRAM is a type of memory that is faster and more reliable than the more common DRAM (dynamic RAM). The term static is derived from the fact that it doesn't need to be refreshed like dynamic RAM.
  
  While DRAM supports access times of about 60 nanoseconds, SRAM can give access times as low as 10 nanoseconds. In addition, its cycle time is much shorter than that of DRAM because it does not need to pause between accesses. Unfortunately, it is also much more expensive to produce than DRAM. Due to its high cost, SRAM is often used only as a memory cache.
   
• SSL: (Secure Sockets Layer)
  A protocol designed by Netscape Communications to enable encrypted, authenticated communications across the Internet. SSL is used mostly in communications between Web browsers and Web servers. URLs that begin with "https" indicate that an SSL connection will be used.
   
• Static:
  As a web site term, this is used to describe a web page that is not interactive. The webmaster writes information to the source code of a web page and can only be changed by re-writing the source code. A visitor to the web page cannot manipulate its contents.
   
• Steganography:
  This refers to a method of concealing data inside of data. The secret information can be hidden inside of an image or sound file so that a normal user would not know that it existed.
   
• Streaming:
  A technology that involves the playing of audio or video files in real time over the Internet.
   
• Subroutine:
  A procedure that performs a specific function; usually a process that may be needed several times or a routine that may be used in several different programs. For example, many subroutines have been created to parse URL-encoded data.
   
• Subscriber Unit (SU):
  An alternate term for cable modem.
   
• SuperFetch:
  A memory management technology in Windows Vista that is designed to launch applications more quickly by getting the most out of the available RAM (random access memory). SuperFetch has the ability to learn which applications you use most often so that it can pre-load them into memory.
   
• SVGA:
  Stands for Super Video Graphics Adapter. It's a high level monitor.
   
• Swap File:
  A swap file is an area on your hard disk used as virtual memory. It's called a swap file because virtual memory management software swaps data between it and main memory (RAM).
  
  In the Windows Operating System, a temporary swap file can be configured only when the system needs it. In a Linux and Unix environment, permanent swap files are used which dedicate a certain portion of hard drive space.
   
• Swap Space:
  Disk space used by the kernel as “virtual” RAM. It is slower than RAM, but because disk space is cheaper, swap is usually more plentiful. Swap space is useful to the kernel for holding lesser-used data and as a fallback when physical RAM is exhausted.
   
• Switch:
  In networks, a device that filters and forwards packets between LAN segments. Switches operate at the data link layer (layer 2) of the OSI Reference Model and therefore support any packet protocol. LANs that use switches to join segments are called switched LANs or, in the case of Ethernet networks, switched Ethernet LANs. 
  
  A small lever or button. The switches on the back of printers and on expansion boards are called DIP switches. A switch that has just two positions is called a toggle switch. 
  
  Another word for option or parameter -- a symbol that you add to a command to modify the command's behavior. 
   
• Switching Hub:
  A high-performance hub, also called a "switching hub" that can recall what devices are connected to each port and transfer necessary data to the required port. Unlike the conventional hub, which sends data to every port.
   
• Synchronize:
  Refers to two or more elements, events or operations programmed to occur at a predefined moment in time or place.
   
• Synchronous:
  Synchronous can refer to: (1) A communications method that transmits a group of characters as a block of data rather than as individual characters. (2) A reference to the fact that two different data streams are tied, or synchronized, to a single reference clock. (3) Data transmitted in a time-division multiplexer.
   
• Syntax:
  Grammatical structuring of data using a special code that defines how this special code is used to form words, phrases or any other allowable constraint.
   
• System:
  A combination of the hardware, software, and firmware. A system typically consists of components (or elements) which are connected together in order to accomplish a specific function or set of functions. 

S